The Galapagos archipelago
lies 1000 kilometers (600 miles) west of Ecuador and 1500 kilometers
(900 miles) southwest of the Panama Canal. Geologically the islands
sit on the Galapagos rift, an offshoot of the East Pacific Rise. The
chain of young volcanic islands — 13 large islands and many
smaller ones — straddles the equator and stretches between
1° north
and 1°3'
south and lies between 89° and 92° west
longitude. With the exception of Isabella, the largest island, the
islands are roughly circular in shape with high volcanic craters at
the island centers, some rising to 1520 meters (5000 feet). Numerous
eruptions have taken place on the islands within historic times. However,
the detailed geology of the islands is only now coming under investigation,
since most are extremely inaccessible. A major eruption on Fernandina
Island in 1974 went unnoticed on the ground until it was observed from
the Skylab 4 spacecraft.

The islands are largely desolate lava piles with little vegetation along the coasts, but the high volcanic mountains generate rains that have mantled the summits with dense jungle. In the photograph clouds can be seen forming over the high points of individual islands. The islands are famous not only for their volcanic associations but also for the peculiar flora and fauna that result from isolation from any continental mainland.